Diagnostic Ultrasound - Abdomen and Pelvis

Tuberculosis, Urinary Tract
TERMINOLOGY
Abbreviations
• Urinary tract tuberculosis (TB)
Synonyms
• Renal TB, urinary bladder tuberculosis
Definitions
• Urinary tract infection (UTI) by mycobacterium tuberculosis
via hematogenous spread from primary focus, usually lungs
• Ureteral and bladder disease are secondary to renal
involvement
• Earliest form of bladder TB starts around ureteral orifice
IMAGING
General Features
• Best diagnostic clue
○ Depends on stage of disease; may range from caliectasis,
abscess, cavities, calcifications, and strictures in urinary
tract
• Location
○ Kidney, ureter, and bladder (~ 14-41% of extrapulmonary
TB)
○ Usually bilateral involvement but can also be unilateral
Ultrasonographic Findings
• Grayscale ultrasound
○ Appearance is nonspecific and variable based on stage
○ Early: Normal kidney or small focal cortical lesions with
poorly defined border ± calcification
○ Progressive
– Papillary destruction with echogenic masses near
calyces
– Distorted renal parenchyma, manifest as
pyelonephritis with edematous kidney
– Irregular hypoechoic masses connecting to collecting
system (pseudotumor)
– Mural thickening ± ureteric and bladder involvement,
associated stricture → hydronephrosis
– Small, fibrotic, thick-walled bladder
– Echogenic foci or calcification (granulomas) in bladder
wall near ureteric orifice
○ Late
– Small, shrunken kidney, "paper-thin" cortex and
dystrophic calcification in collecting system
– May resemble chronic renal disease
○ US less sensitive than CT in detection of isoechoic
parenchymal masses, small cavities, calyceal/ureteral
abnormalities
○ US unable to evaluate renal function
○ Useful to evaluate pelvic inflammation, especially in
women
Radiographic Findings
• IVP
○ Early: Irregular calyceal contour due to erosion motheaten
appearance
○ Progressive
– Irregular tract formation from calyx to papilla
– Large irregular cavities with extensive destruction due
to papillary necrosis
– Hydrocalyces or "phantom calyx" (nonopacification of
calyx due to infiltration and obliteration) proximal to
infundibular stricture
– Sharp kink at pelviureteric junction due to scarring
("Kerr kink")
– Delayed contrast excretion
– Fibrosis and stricture of renal pelvis or ureter →
beaded ureter, focal calcification, or hydronephrosis
– Small volume bladder
○ Late
– Heavily calcified caseous mass surrounded by thin
parenchymal shell → "putty kidney"
– Small, shrunken, scarred, nonfunctioning kidney with
dystrophic calcification (autonephrectomy)
CT Findings
• CECT
○ CECT with CT urogram (CTU) is useful in diagnosing and
assessing severity
○ Moth-eaten calyces, cavities, and renal parenchymal
masses better appreciated
○ Amputated infundibulum due to stricture
○ Assessment of renal function (delayed nephrogram and
contrast excretion)
○ Multifocal ureteral stricture causing hydronephrosis
○ Better assessment of wall thickening and calcification
along urinary tract
○ Late stages: Small, poor-functioning, scarred kidneys
with dystrophic calcification
○ Better assessment of extrarenal manifestation in
retroperitoneum and pelvis
Imaging Recommendations
• Best imaging tool
○ IVP described to have high sensitivity (88%) in detecting
TB manifestation; in fact, majority of imaging features
have been described on IVP
○ CECT with CTU has been shown to be more useful in
assessing the severity and extrarenal complications
– CTU may evolve as preferred imaging modality in
evaluation of GU TB
○ Ultrasound: Often used for monitoring disease
progression and complication (like hydronephrosis)
• Protocol advice
○ IVP described as primary investigation; however, CT
(CTU) may evolve as a preferred imaging modality in
diagnosis and evaluation of complications and extrarenal
manifestation; US useful in assessing complications
(renal abscess, hydronephrosis)
DIFFERENTIAL DIAGNOSIS
Papillary Necrosis
• Sonographically, necrotic papilla depicted as echogenic
nonshadowing lesion surrounded by fluid in medulla
Pyonephrosis
• Dependent echoes and fluid debris level within dilated
collecting system
• Gas within collecting system
Diagnoses: Urinary Tract
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